Harriet Maltby is a Government and Economics Researcher at the Legatum Institute and a former Senior Parliamentary Assistant.

As Britain overtakes France to become the fifth biggest economy in the world, George Osborne has the economic might of the USA in his sights. But whilst the Chancellor talks of GDP at home, David Cameron stands beside Obama to talk of the future of our nations’ prosperity in the face of grave threat.

The two British politicians, of course, cannot be separated and the economy is one area in which the UK still significantly trails the US in the Legatum Prosperity Index. If Cameron is serious about national prosperity, the focus on strengthening the economy cannot falter.

Yet prosperity and wealth are not interchangeable terms. Prosperity is multi-faceted, and is about more than just GDP. Wellbeing matters too. Whilst the economy forms one key pillar of prosperity within our Index, there are seven others of equal weight. They encompass the other themes touched upon by the Prime Minister and President – such as freedom, innovation, and security, but they also include civil society, health, education, and governance.

Osborne’s prediction that Britain could be wealthier than the US by 2030 may sound ambitious, but the UK has the potential to become more prosperous than America a lot sooner than that.

This year, the Index ranked the UK 13th out of 142 global countries for prosperity to the USA’s 10th. The US has seen little change in its overall prosperity score since 2009, but the UK has improved. We’re gathering speed and we’re catching up. If average trajectory continues, UK prosperity could overtake that of the US within four years.

Five years ago, the UK led America in just one of the eight pillars measured in the Prosperity Index (Safety & Security). Since then, we have overtaken the US in another three. Not only that, Britain is riding roughshod over the American Dream. Just five years ago, America was freer, better governed, and offered a better environment for entrepreneurship and opportunity than the UK.

Not anymore. The Land of the Free sits outside the top 20 for Personal Freedom for the first time ever in the 2014 Index. Whilst in 2008 Americans used to be far more satisfied with freedom of choice and civil liberties than the British (87 per cent v 70 per cent), today just 75 per cent of Americans feel satisfied. In the UK it is 91 per cent.

Despite strong dedication to the institutions and values of the American Constitution, confidence in institutions in the US has been on the slide, whilst corruption is on the rise. As a result, Britain is now better governed than the US, with higher public confidence in institutions like the military, elections, and the courts.

Perhaps most damaging to the American Dream is the relative decline of entrepreneurship and opportunity in America. The percentage of Americans with adequate access to food and shelter was 87 per cent in 2009, but 82 per cent today. In the UK, it has remained static at 93 per cent. Satisfaction with living standards is higher in the UK and economic development is far more equitable. Whilst America has traditionally been far more confident that working hard can get you ahead in life than the British, today the difference is within the poll’s margin of error. As a result, Britain has pulled ahead.

Britain’s business environment for the innovative and entrepreneurial has also caught up with and surpassed the US. Here the divergent routes taken by our governments are laid clear. We had the same business start-up costs in 2009. The UK aggressively cut them whilst the US put them up. R&D investment in the US has fallen, whilst in the UK it has risen to the point where Britain now invests more than the US. Policy matters for prosperity, and the UK Government has taken steps to improve not hinder it.

America still has the edge on health and education. The disparity on health is mainly due to very high spending per head on healthcare in the US. When we look just at outcome measures like life expectancy, the difference is far less marked. Indeed, we spend over two and a half times less on health per head than the States, but Britons live longer, worry less, and are more satisfied with their health than Americans.  In education, the transatlantic gap is closing as American satisfaction with the standard of its school system falls. Britain still lags on tertiary education and class size, but satisfaction with quality has risen.

As the Americans fought for their independence, Thomas Paine said that “these are the times that try men’s souls”. Now standing side by side, our two nations face such times again as our national prosperity feels the challenge of grave threat. On current trajectory, this time it is Britain that may emerge as the natural home for the free and prosperous citizen.